Standard fall

The standard fall is used to measure the strength of climbing ropes and to determine parameters such as the number of falls . To do this, a fall into a rope is simulated as a mountain accident in the laboratory . All climbing ropes sold today must withstand at least 5 such standard falls, some can also be loaded with more falls.

The standard fall is defined in the European standard EN 892. A certain weight is dropped from a certain height and has to be slowed down by the rope. The rope is deflected in a carabiner with a radius of 5 mm. The end of the rope is fixed, so the fall is held statically (i.e. no belay device is used that, above a certain force, has a rope passage where the fall energy is converted into heat by friction ). The only dynamic element in this system that can absorb the kinetic energy of the sample weight is the rope, the characteristics of which are measured:

• When braking, a certain force ( impact force ) must not be exceeded
• the rope must not stretch more than a certain factor .

The rope length issued for a standard fall is 2.80 m, of which 30 cm between the rope fixation and the deflection carabiner. Before the weight is released, it is 2.30 m above the deflection. The free fall height (before the rope begins to brake the fall) is therefore a maximum of 2.30 m + 2.50 m = 4.80 m. However, the 2.80 m is a stretched rope that has been statically pre-stretched for 60 seconds with the falling mass. The rope may be stretched a maximum of 12% (unstretched 2.50 m, i.e. stretched by 30 cm to 2.80 m), resulting in a free fall height of at least 2.30 m + 2.50 m - 30 cm = 4.50 m results.

The fall factor  f that occurs (free fall height divided by the unloaded rope length) can only be given approximately, as the standard fall conditions only define the loaded rope length, but not the unloaded rope length. Depending on the static pre-stretching of the rope, the fall factor is between 1.71 (no pre-stretching) and 1.80 (12% pre-stretching).

The load in a standard fall is so extreme that it almost never occurs in practice. This means that a rope that can still hold a standard fall cannot break in practice (exception: loading via a sharp edge).

Depending on the type of rope, different requirements apply to a standard fall:

Rope type	Sample mass	strand	static pre-elongation max.	permissible impact force on the first fall max.	Number of impacts min.
Half ropes	55 kg	Single strand	12%	8 kN	5
Single ropes	80 kg	Single strand	10%	12 kN	5
Twin ropes	80 kg	Double strand	12%	12 kN	12

The greatest possible fall load on the bolt is around 16 kN when climbing. This value is definitely achieved if you fall into the first hook with a static safety device (e.g. Grigri ). In this case, the load on the hook is slightly less than twice the impact force.

Strength is just one parameter of a good rope. At least as important is the stretch , which must be more than 9% under load in order to survive a fall .

literature

• European Committee for Standardization: Önorm EN 892, Ident (IDT) with EN 892: 2004 . Mountaineering equipment - Dynamic mountain ropes - Safety requirements and test methods. 2004 ( PDF [accessed July 25, 2012]).

Individual evidence

1. ^ Pit Schubert : Standard testing of mountain ropes . In: German Alpine Association , Austrian Alpine Association , Alpine Association South Tyrol , Swiss Alpine Club (publisher): bergundstieg . No.  2 . Innsbruck 2003, p. 42-49 .
2. ↑ European Committee for Standardization: Önorm EN 892, Ident (IDT) with EN 892: 2004 . Mountaineering equipment - Dynamic mountain ropes - Safety requirements and test methods. 2004, p. 17 ( PDF [accessed July 25, 2012]).
3. ↑ ig-klettern.com (PDF; 212 kB)
4. ↑ alpenverein.at (PDF; 724 kB)